A typical surgical stapler apparatus comprises a handle at a proximal end and two elongated jaw-like members joined together at a hinge at a distal end. The jaw-like members articulate to open and close to capture tissue between the jaw-like members. The user controls the device from the handle to open and close the jaw-like members, actuate deployment of staples and in general manipulate and control the device. One of the jaw members carries a disposable cartridge containing staples arranged in two or more rows. The other one of the jaw-like members comprises an anvil against which the staples are driven to deform the staple legs. Staples are driven out of the cartridge by a caming surface or slider that moves longitudinally against a plurality of laterally positioned pushers that push each staple out of the cartridge individually. The caming surface of the slider is angled to compliment the angular surface of the pushers. The cooperation between the angular surfaces of the pushers and the slider is a key step of the surgical stapling process. Misalignment can cause the staples to jam the device. Some staplers include a blade that follows the caming surface so as to cut the tissue between the two or more rows of delivered staples.
Surgical staplers are used in a variety of surgical techniques including laparoscopic and/or endoscopic or other minimally invasive surgical procedures in which the stapler is inserted through a cannula or tube positioned within a small incision in a patient's body. In laparoscopic, endoscopic or minimally invasive surgery, a trocar or cannula is inserted across body tissue of a patient to access a body cavity and to create a channel for the insertion of a camera, such as a laparoscope. The camera provides a live video feed capturing images that are then displayed to the surgeon on one or more monitors. Additional trocars are inserted to create additional pathways through which surgical instruments, including surgical staplers, can be inserted for performing procedures observed on the monitor. The targeted tissue location such as the abdomen is typically enlarged by delivering carbon dioxide gas to insufflate the body cavity and create a working space large enough to accommodate the scope and instruments used by the surgeon. The insufflation pressure in the tissue cavity is maintained by using specialized trocars having seals that prevent the insufflation gas from escaping and collapsing the surgical working space. Laparoscopic surgery offers a number of advantages when compared with an open procedure. These advantages include reduced pain and hemorrhaging and shorter recovery times.
As laparoscopic surgery evolves to become even more minimally invasive with incisions and cannula diameters becoming smaller and smaller, surgical staplers for use in laparoscopic/endoscopic procedures must be designed to fit within the small lumen of a cannula. Generally, a surgical stapler is inserted into a cannula such that the jaw-like members are in a closed orientation to inside the patient where the jaw-like members are opened to grasp and staple tissue. The handle of the stapler resides outside of the patient in control of the surgeon user. A portion of the shaft of the stapler between the jaw-like members and the handle is long enough to extend from outside the patient to inside the patient. During the surgical procedure, the elongate shaft of the stapler resides inside the cannula into which it was inserted. The distal jaw-like members include many components such as an anvil for forming staples, a staple cartridge with a plurality of staples, a caming surface such as a slider, pushers, a blade and other components which must all be small enough to fit through a small diameter cannula and made to function reliably and repeatedly from outside the patient. While conventional laparoscopic staplers are approximately 12 millimeters in diameter, the present invention provides a surgical stapler designed to fit inside a cannula having a diameter as small as approximately 5-10 mm.